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Keycard repair

Posted: Fri Apr 09, 2010 8:47 pm
by triumph2.5man
Hi folks! More about the dreaded keycard! Ours packed up last year and although I attempted to repair it myself, I was forced to give up! Symptoms started off with "replace battery" which I duly did. After a short time the message reappeared and there was a lot of switching batteries from one card to another. This was when the card would no longer start the car (but would still lock and unlock.) There was no message, no "card not recognised" etc. Inserting the card failed to make any difference to the "insert card" instruction. Was the erroneous "low battery" message related to the inability to start the car? I did wonder. The spare card worked Ok so I knew there was no problem with the reader.
As I am sure you know, to start the car it is not necessary to have a battery in the card. The transponder is a RFI (radio frequency interference) device which responds to radio waves from an outside source. Your dustbin has one, to weigh your rubbish! Aeroplanes have them and these are given "squawk" codes to identify them to ATC. (Sorry if I am teaching my granny to suck eggs here.....!)
So the keycard does not need a battery to start the car. However the micro-circuitry does provide a link between the battery and the transponder. How do you think the card reader knows when your lithium battery is getting low? The transponder provides this information, even though it does not need the voltage to function.

I opened the case of the card very carefully and using a miniature soldering iron, checked all the joints for breakages or the electronic engineers' nightmare, dry joints. The former are visible, the latter are not. I could find no faults.
At the Renault dealer, the card was inserted in a reader and found to contain no information at all. I assumed the transponder had lost its memory, for whatever reason.
At this point, faced with paying Monsewer Renault 150 quid, I sent the card with £20 to keycardrepair.co.uk. somewhere in darkest Whales, sorry Wales! I had previously corresponded with Gary and expressed the opinion that I thought he would be unable to repair it, inviting him to prove me wrong. Here I am eating humble pie by the shovel load! The darned thing came back a few days later - WORKING!!!
The transponder had not lost its memory. All the info was still there! To understand this, it is necessary to grasp how the system works. See the attached photo and identify the large black coil at the bottom. This is the "receiving coil" which passes info to the transponder and back. If this is not connected then it follows that the transponder will not respond (sorry that's a bit obvious!) The coil is held by three connections. Number 1 is to hold it to the card. Numbers 2 and 3 provide the electrical connection. Sometimes these 2 connections breakaway from the PCB.
If you remove the coil, it will not affect the central locking, as I discovered.
So what was wrong with our coil? (Dave, at this point I must say that I may be the "voice of experience", but I still have a lot to learn!!) It appears that, despite using care, I caught the coil with the blade of Mr Stanley while opening the case and broke a wire!! Curses, but the coil is very close to the edge of the case. Well that is my excuse! But I am sure I checked the continuity of the coil windings with a meter between 2 and 3.....? Memory is not what it was...

Before I wrap up this "diabolical diatribe" I must mention that other members covered this "coil" aspect last year - Mondo9 and Ulrich100. How I wish I had read these beforehand but I was not then a member. I particularly liked Ulrich's method of heating the case to soften the adhesive holding the two parts together. That's a good one and well worth remembering.

Sorry to bore you but if you have card problems and don't fancy tackling them yourself, do get in touch with Gary at the above address. Without giving away any secrets, how does he know your card works before he sends it back since he cannot try it in the car itself? He checks the locking function using a frequency of 455mhz, and a card reader to interrogate the transponder. Seemples!
Sorry to bore you. Have you learned owt? Did you get to the end.....?
Cheers all, Mike



Image

Re: Keycard repair

Posted: Fri Apr 09, 2010 10:37 pm
by davelowe
Fascinating read once again Mike!

Maybe the 'voice of experience' term is a little overused. Mr. Stanley and soldering irons are the kind of thing I'm good at. It's the bigger things that get me foxed (new rear disc anyone?)!

I suspect that the transponder is a simply half an air filled coil and in conjunction with any similar oscillating signal source, will relay a code between itself and the rest of the electronics on the card. The electronics is probably the source of the 'security'.

You could probably check this by sticking a few loops of enamelled wire in the card reader slot and hooking the ends up to an oscilloscope...

Re: Keycard repair

Posted: Sat Apr 10, 2010 6:31 pm
by triumph2.5man
Dave I can see you are very interested in electronics. The following will interest you. The transponder is actually incorporated in a chip (IC) either pcf7947 or pcf7943. If you "Google" these two you will find out all about them. It is possible to purchase and fit a new chip and I suspect this is what the repair guys do when they "virginise" a card. You will also see for sale they equipment that is used. Note this immobiliser kit is also used by other car manufacturers.
Enjoy!
Cheers, Mike

Re: Keycard repair

Posted: Sat Apr 10, 2010 10:38 pm
by davelowe
I WILL learn! Of this, more hereafter! Respect 8-)

Re: Keycard repair

Posted: Tue Jun 29, 2010 8:11 pm
by chewbacker
hi guys
if i un solder the pcf chip from my dodgy keycard and fit it in place of a pcf ou of a working keycard
is there any danger that the heat involved in removing and re soldering the chip may damage it and prevent
it from working.
my keycard only has a replace battery fault but after opening my card and checking the board i can see no problems so
am thinking it's a micro capaciter failing. any ideas would be great

Re: Keycard repair

Posted: Wed Jun 30, 2010 10:13 am
by tomalamix
Hi guys,

I advise you to go to this thread here: viewtopic.php?f=2&t=13778#p84778

You will find more info about this cards.

About the PCF exchange i think you're pretty safe as long as you use a soldering iron with 20Watts or very similiar (its better not to pass this barrier). I desoldered and soldered back many chips and never had a single problem, except with the soldering it self, i.e., bad jointed interfaces or something like that, but after all the chips went through the heat just fine.

I'm interested in your results when changing the PCF to an other card. Please post your results.

PS: Does anyone know where to buy those coils? And the push-button to lock\unlock?

Cheers!

Re: Keycard repair

Posted: Wed Jun 30, 2010 10:03 pm
by Paddy
Evening Mike.

That was indeed a educational read. It highlighted a few interesting points that i was unaware of.

However i took the easy way out when my second key packed in also. I took out the AA break down cover for £49.99, then used it to have 2 brand new keys delivered for an excess of only £25. I still have 4 clams left this year up to £500 with an excess of £25. It’s a fantastic service.

Many thanks for the informative read.
Patrick

Re: Keycard repair

Posted: Thu Jul 01, 2010 5:20 pm
by snowy

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Re: Keycard repair

New postby ulrich100 » Wed Jun 30, 2010 10:03 pm
Evening Mike.

That was indeed a educational read. It highlighted a few interesting points that i was unaware of.

However i took the easy way out when my second key packed in also. I took out the AA break down cover for £49.99, then used it to have 2 brand new keys delivered for an excess of only £25. I still have 4 clams left this year up to £500 with an excess of £25. It’s a fantastic service.

Many thanks for the informative read.
Patrick


great idea. very clever of you! what exactly did you take out with the AA, as i might do this!

Re: Keycard repair

Posted: Thu Jul 01, 2010 5:57 pm
by tomalamix
AA? Whats the AA?

Re: Keycard repair

Posted: Thu Jul 01, 2010 8:57 pm
by Paddy
tomalamix wrote:AA? Whats the AA?



Alcoholics Anonymous -- Its a great recovery / break down service.

Re: Keycard repair

Posted: Thu Jul 01, 2010 10:12 pm
by davelowe
ulrich100 wrote:
tomalamix wrote:AA? Whats the AA?



Alcoholics Anonymous -- Its a great recovery / break down service.


You monkey!! Tell him the truth now.......! :wink:

Re: Keycard repair

Posted: Thu Jul 01, 2010 11:55 pm
by Paddy
snowy wrote:

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Re: Keycard repair

New postby ulrich100 » Wed Jun 30, 2010 10:03 pm
Evening Mike.

That was indeed a educational read. It highlighted a few interesting points that i was unaware of.

However i took the easy way out when my second key packed in also. I took out the AA break down cover for £49.99, then used it to have 2 brand new keys delivered for an excess of only £25. I still have 4 clams left this year up to £500 with an excess of £25. It’s a fantastic service.

Many thanks for the informative read.
Patrick


great idea. very clever of you! what exactly did you take out with the AA, as i might do this!


I have full AA cover. Then i added the break down cover for £49.99. After 14 days it allows you to make a claim for Mechanical or Electrical faults 'that stop you progressing on you journey' (sorry window regs arn't included :()it caries a compulsory excess of £25 for a claim to the amount of 5 a year to the value of £500 including vat. IMO, a steal if your car is out of warranty.

Re: Keycard repair

Posted: Fri Jul 02, 2010 9:14 am
by tomalamix
AA...what does it mean? For some ppl is used to treat alcohol dependency but for the rest of the ppl what it stands for?

Re: Keycard repair

Posted: Fri Jul 02, 2010 8:36 pm
by Paddy
Its the Automobile Association. They are a break down company thtat services the UK.

See... https://www.theaa.com/

Re: Keycard repair

Posted: Fri Jul 02, 2010 10:17 pm
by davelowe
Neglected factoids about the AA:

1. They used to issue proper chrome style badges that you would fix to the front of your car (1950s style).
2. If an AA 'official' was to pass your car in the opposite direction, they were required to salute you military style on seeing the badge.

Source: my dad